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Tubular Bandpass Filters

Bandpass Filter Part Number Description

Tubular Filter Part Number Description


1. Number of Sections

2. Series and Package Size

3. Center Frequency, MHZ

4. Bandwidth and Designator (3dB BW Standard)

5. Input Connector

6. Output Connector (if different from Input)

(1) 6" RG 188 Standard
(2) Requires SMA Removable Connectors at High Frequencies

Bandwidth Designator
3 dB /(blank)
1 dB /A
equi-ripple /R
special /X
Connectors
Connector Type Designator
BNC - M BM
BNC - F B
Type N - Male NM
Type N - Female N
TNC - Male TM
TNC - Female T
SMA - Male SM
SMA - Female S
Overview
Bandpass
Lowpass
Dimensions



Tubular Bandpass Filters
P/N Freq.
Range
(MHz)
% 3 db
Bandwidth
VSWR
(Typical)
Number of
Sections
Avg. Power
(Watts)
Operating
Temp. (Deg. C)
Impedance Relative
Humidity
BA 200-5000 5 - 50 1.5:1 2 - 10 2 -40 to +85 50 0 - 95%
BC 75-2500 5 - 50 1.5:1 2 - 10 15 -40 to +85 50 0 - 95%
BD 50-1500 5 - 50 1.5:1 2 - 10 40 -40 to +85 50 0 - 95%
BE 50-500 5 - 50 1.5:1 2 - 10 200 -40 to +85 50 0 - 95%


Calculating Number of Sections
The following curves show the stopband frequencies normalized to the 3 dB bandwidth for filters with 2 to 8 sections. A ratio of stopband frequency to 3 dB bandwidth is used.

he curve given on the right shows an asymmetric frequency response resulting from the circuit used. Other schematics may be utilized to yield different attenuation characteristics (i.e. steeper on the high frequency side of the passband and shallower on the low side).

Example:
A BC-Series filter has a center frequency of 1000 MHz and a 3 dB bandwidth of 50 MHz. Use the curve for 3-10% bandwidth filters. A stopband attenuation of 40 dB is required at 760 MHz and 50 dB is required at 1140 MHz.

The percentage bandwidth is 5%, calculated as follows:

Example 1

For the first stopband requirement:

Example 1

Number of 3 dB bandwidths from center frequency =

Example 1

From the 3-10% bandwidth attenuation curve, we find that a minimum of 3 sections is required.

The second stopband requirement is:

Number of 3 dB bandwidths from center frequency =

Example 1

From the 10-50% bandwidth attenuation curve, we find that 4 sections minimum are required.

The greater number of sections must be used to insure full specification compliance; therefore, a 4 section should be used.

Insertion Loss Calculation:
Knowing the number of sections, center frequency and bandwidth of the filter, insertion loss may be calculated using the following formula:

Example: 4BC - 1000/150-S
1. Percentage BW = 50/1000 x 100 = 5%
2. LC from table = 2.5
3. Number of Sections (from P/N) = 4
4.

Bandpass Attenuation Chart 1
 
  Bandpass Attenuation Chart 1
 
 
Tubular Bandpass Filter Dimensions
Model LPF Model Diameter
Inches / mm
BA LA .25 / 6.35
BC LC .50 / 12.7
BD LD .75 / 19.05
BE LE 1.25 / 31.70

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